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Home >> GMC >> 1990 >> Forward Control 4.3 Z, Automatic, 475/M40 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - TBI >> Diagnostic Tests >> Code 32: EGR System Error 2.5L/5.0L/4.3L Except S & T) & 5.7L (Less Than 8500 GVWR) >> Notes
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Code 32: EGR System Error 2.5L/5.0L/4.3L Except S & T) & 5.7L (Less Than 8500 GVWR): Notes

ECM controls a solenoid regulating vacuum to the EGR valve. The normally closed solenoid prevents vacuum from passing until it is energized by ECM. A properly operating EGR will directly affect fuel integrator counts. With EGR valve open, integrator counts will be less than without EGR operation. If monitored integrator counts do not change with EGR commanded, Code 32 will set.

NOTE: Test numbers refer to test numbers on diagnostic chart.

Test Number 1)  When test terminal "B" of the ALDL connector is grounded, EGR solenoid should be energized, allowing vacuum to the EGR valve. Vacuum should hold.

Test Number 2)  SERVICE ENGINE SOON light should also flash while diagnostic terminal is grounded. If SERVICE ENGINE SOON does not operate it may indicate the Quad-Driver damage by low TCC circuit resistance.

Test Number 3)  When jumper wire is removed from terminal "B", vacuum to the EGR valve should bleed through a vent in the solenoid and EGR valve should close. Vacuum gauge may or may not bleed off vacuum, however, this does not indicate a problem.

Test Number 4)  Determines if fault lies in electrical control part of the system, connector or solenoid.

Test Number 5)  This system uses a negative backpressure EGR valve. Valve should hold vacuum with engine off.

Test Number 6)  When engine is started, backpressure should cause vacuum to bleed off and valve should fully close.